The invention relates to transparent casting resin compositions for sealing opto-electronic components on the basis of acid anhydride-hardenable epoxy compounds with at least two oxiran rings in the molecule, together with organo-metallic compounds, low-molecular polyols and/or low-molecular acid esters and, optionally, with organic phosphorus compounds, optical brighteners, pigments and light-scattering materials in powder form.
It is known to use, for covering or coating opto-electronic components, light-permeable, acid anhydride-hardenable epoxy casting resin compounds of the bisphenol-A type (German Offenlegungsschrift No. 589 264 =U.S. Pat. No. 3,544,827).
One disadvantage of epoxy casting resin compounds based on bisphenol-A/acid anhydride, which harden fast through the use of known accelerators such as tertiary amines, imidazoles or borofluoride complexes, is their poor thermal aging stability. The materials used heretofore become discolored in extended storage at temperatures above 80.degree. C., through yellow to brown, whereby their light transmittancy decreases considerably.